Improve the install generator to handle two- and three-tier database.yml config files

lib/generators/solid_cache/install/install_generator.rb

@@ -13,10 +13,12 @@ def create_config_solid_cache_yml
   end
 
   def add_cache_db_to_database_yml
-    if app_is_using_sqlite?
-      gsub_file database_yml, /production:\s*<<: \*default.*/m, sqlite_database_config_with_cache
+    if two_tier_production_configuration?
+      append_cache_db_to_two_tier_configuration
+    elsif three_tier_production_configuration?
+      append_cache_db_to_three_tier_configuration
     else
-      gsub_file database_yml, /production:\s*<<: \*default.*/m, generic_database_config_with_cache
+      append_configuration_comment
     end
   end
 
@@ -33,40 +35,133 @@ def database_yml
       app_root.join("config/database.yml")
     end
 
-    def app_is_using_sqlite?
-      database_yml.read.match?(/production:.*sqlite3/m)
+    def database_config
+      @database_config ||= YAML.load(database_yml.read, aliases: true)
     end
 
-    def sqlite_database_config_with_cache
-      <<~YAML
-        production:
-          primary:
-            <<: *default
-            database: storage/production.sqlite3
-          cache:
-            <<: *default
-            database: storage/production_cache.sqlite3
-            migrations_paths: db/cache_migrate
-      YAML
+    def production_block
+      return @production_block if defined? @production_block
+
+      production_block_regex = %r{
+        \nproduction:    # Match 'production:' at the start of a line
+        (?:              # Start of non-capturing group for block
+          \n             # Match newline
+          (?:            # Start of another non-capturing group for lines
+            [ \t]+.*     # Match indented lines (one or more spaces/tabs, then any content)
+            |            # OR
+            [ \t]*       # Match blank lines (any number of spaces/tabs, including none)
+          )
+        )*               # End of outer group, repeat 0 or more times
+      }x
+      @production_block = database_yml.read[production_block_regex]
     end
 
-    def app_name_from_production_database_name
-      database_yml.read.scan(/database: (\w+)_production/).flatten.first
+    def deconstruct_production_block
+      newline, name, *contents = production_block.split "\n"
+      indentation = contents.first[/^([ \t]*)\S/, 1]
+
+      [indentation, newline, name, *contents]
+    end
+
+    def two_tier_production_configuration?
+      database_config["production"].key?("adapter")
+    end
+
+    def append_cache_db_to_two_tier_configuration
+      indentation, newline, name, *contents = deconstruct_production_block
+      app_name = app_name_from_production_database_name
+
+      if database_config.dig("production", "adapter") == "sqlite3"
+        output = [
+          newline,
+          name,
+          "#{indentation}primary:",
+          *contents.map { |it| "#{indentation * 2}#{it.strip}" },
+          "#{indentation}cache:",
+          "#{indentation * 2}<<: *default",
+          "#{indentation * 2}database: storage/production_cache.sqlite3",
+          "#{indentation * 2}migrations_paths: db/cache_migrate",
+          ""
+        ]
+      else
+        output = [
+          newline,
+          name,
+          "#{indentation}primary: &production_primary",
+          *contents.map { |it| "#{indentation * 2}#{it}" },
+          "#{indentation}cache:",
+          "#{indentation * 2}<<: *production_primary",
+          "#{indentation * 2}database: #{app_name}_production_cache",
+          ""
+        ]
+      end
+
+      gsub_file database_yml, production_block, output.join("\n")
+    end
+
+    def three_tier_production_configuration?
+      database_config["production"].key?("primary")
+    end
+
+    def append_cache_db_to_three_tier_configuration
+      return if database_config["production"].key?("cache")
+
+      indentation, newline, name, *contents = deconstruct_production_block
+      app_name = app_name_from_production_database_name
+
+      if database_config.dig("production", "primary", "adapter") == "sqlite3"
+        output = [
+          newline,
+          name,
+          *contents,
+          "#{indentation}cache:",
+          "#{indentation * 2}<<: *default",
+          "#{indentation * 2}database: storage/production_cache.sqlite3",
+          "#{indentation * 2}migrations_paths: db/cache_migrate",
+          ""
+        ]
+      else
+        primary = contents.find { |it| it.match?(/^([ \t]*)primary:.*$/) }
+        primary_alias = primary[/primary:\s*&([^ \t]*)/, 1] || "default"
+
+        output = [
+          newline,
+          name,
+          *contents,
+          "#{indentation}cache:",
+          "#{indentation * 2}<<: *#{primary_alias}",
+          "#{indentation * 2}database: #{app_name}_production_cache",
+          ""
+        ]
+      end
+
+      gsub_file database_yml, production_block, output.join("\n")
     end
 
-    def generic_database_config_with_cache
+    def append_configuration_comment
       app_name = app_name_from_production_database_name
 
-      <<~YAML
-production:
-  primary: &production_primary
-    <<: *default
-    database: #{app_name}_production
-    username: #{app_name}
-    password: <%= ENV["#{app_name.upcase}_DATABASE_PASSWORD"] %>
-  cache:
-    <<: *production_primary
-    database: #{app_name}_production_cache
-      YAML
+      append_to_file "config/database.yml", <<~TEXT
+        # You need to add the following configuration to your production environment configuration:
+        #
+      TEXT
+      if database_yml.read.include?("adapter: sqlite3")
+        append_to_file "config/database.yml", <<~TEXT
+          # cache:
+          #   <<: *default
+          #   database: storage/production_cache.sqlite3
+          #   migrations_paths: db/cache_migrate
+        TEXT
+      else
+        append_to_file "config/database.yml", <<~TEXT
+          # cache:
+          #   <<: *production_primary
+          #   database: #{app_name}_production_cache
+        TEXT
+      end
+    end
+
+    def app_name_from_production_database_name
+      database_yml.read.scan(/database: (\w+)_production/).flatten.first
     end
 end